Drafting instrument for zigzag lines

ABSTRACT

A base member has a flat back surface adapted to be placed against a paper sheet on which lines are to be drawn, and also has a flat front surface provided with a straight shoulder extending across it. The base member has a guide slot through it that is perpendicular to the shoulder and is partly covered by a slide movable along the shoulder. The side of the slide opposite the shoulder has a pair of inclined edges converging toward the center of that side so that when the slide is moved back and forth along the shoulder the inclined edges can be used as guides for drawing lines across the slot that are inclined in first one direction and then the other on the paper sheet to form a zigzag line.

United States Patent 1191 Hopkinson DRAFTING INSTRUMENT FOR ZIGZAG LINES [75] Inventor: Paul O. W. Hopkinson, Gibsonia,

[73] Assignee: St. Barnabas Free Home, Gibsonia,

Pa. a part interest [22] Filed: Dec. 18, 1972 [21] Appl. No.: 316,236

[56] References Cited UNITED STATES PATENTS 686,891 11/1901 Dunbar 33/95 2,247,362 7/1941 Dibble 33/104 FOREIGN PATENTS OR APPLICATIONS 112,582 11/1964 Czechoslovakia 33/108 1451 Apr. 23, 1974 Primary Examiner-Louis R. Prince Assistant Examiner-Richard R. Stearns Attorney, Agent, or FirmBrown, Murray, Flick &

Peckham 5 7 ABSTRACT A base member has a flat back surface adapted to be placed against a paper sheet on which lines are to be drawn, and also has a flat front surface provided with a straight shoulder extending across it. The base member has a guide slot through it that is perpendicular to the shoulder and is partly covered by a slide movable along the shoulder. The side of the slide opposite the shoulder has a pair of inclined edges converging toward the center of that side so that when the slide is moved back and forth along the shoulder the inclined edges can be used as guides for drawing lines across the slot that are inclined in first one direction and then the other on the paper sheet to form a zigzag line.

10 Claims, 3 Drawing Figures 'DRAFTING INSTRUMENT FOR ZIGZAG LINES In mechanical drawing the draftsman often is called upon to draw a zigzag line. Such a line may represent the wire coil of an electrical resistor or it may represent a screw thread. Drawing a neat zigzag line requires that all of the individual inclined lines from which it is formed meet one another at the same angle. This requires considerable care and generally is a relatively slow process.

It is among the objects of this invention to provide a drafting instrument for drawing zigzag lines, which is simple and inexpensive in construction, which is very easy to use, which enables a draftsman to draw a neat zigzag line in which all angles are the same, and with which the individual inclined lines can be made any desired length.

The invention is illustrated in the accompanying drawings, in which FIG. 1 is a front view;

FIG. 2 is an end view; and

FIG. 3 is a front view of a modification.

Referring to FIGS. 1 and 2 of the drawings, a base member with flat front and back surfaces is formed from an L-shape part or member 1 and a flat rectangular plate 2. One end of the laterally projecting portion or leg 3 of the L-shape member overlaps the lower part of the flat rectangular upright portion 4 and may be integral with it. The adjacent edges of this portion and the plate are parallel. The upper edge of leg 3 forms a straight shoulder 5, and the bottom of the leg projecting from upright portion 4 has a rearwardly projecting ledge 7 that is no wider than the thickness of plate 2. The backs of upright portion 4 and the ledge also are in the same plane.

Plate 2 is seated on the ledge and is held in position by a screw 8 that extends through a slot 9 extending lengthwise of the leg. The head of the screw is embedded in the plate so that it cannot turn, and a thumb nut 10 on the front end of the screw clamps the leg and the plate together. When the nut is loosened, the plate can be moved along the ledge in either direction to adjust the width of the gap or guide slot 11 between the plate and the upright portion 4 of the L-shape member.

A slide 13, preferably in the form of a flat plate, rests against the front surface of the base member and also against the shoulder 5. This slide is free to be moved back and forth along the shoulder. The side of the slide opposite the shoulder has a pair of inclined straight edges 14 and 15 converging toward the center of that side. These edges are inclined at the same angle, but in opposite directions. They can be inclined inwardly and toward the shoulder, or inwardly and away from it as shown. Since the angle of the inclined straight edges is the angle at which lines are to be drawn, other slides having straight edges at a different angle than shown can be used at the option of the draftsman.

OPERATION If the zigzag line that is to be drawn is to have an overall width of one-half inch, for example, the base member is adjusted laterally to make the guide slot 11 one-half inch wide and is placed on a sheet of paper on which the line will be drawn. Also, a slide is selected having its straight edges 14 and 15 inclined at the desired angle. The slide is placed on the base member over the guide slot, which is located in the desired position over the paper and held there. Generally, the zigzag line will be drawn from the open end of the guide slot toward its closed end, but it could be in the opposite direction. In either case the slide is moved along the shoulder until one of its inclined edges extends part or all of the way across the slot at the desired starting position. While the slide is held in this position a line is drawn on the paper across the slot along the portion of the inclined straight edge 14 overlying the slot. Assuming that the draftsman is working downwardly in the slot, the slide then is moved across the slot to the left until the other inclined straight edge 15 crosses the lower end of the line that was just drawn. Using the inclined edge as a guide, a second line then is drawn from one side of the slot to the other as shown in dotted lines in FIG. 1. The slide then is reversed again by moving it to the right along the shoulder until a point on the first inclined edge 14 is directly above the lower end of the second line, and then this edge is used as the guide for drawing a third line across the slot. By shifting the slide back and forth in this manner, the slide being moved further each time to bring progressively lower points on the inclined edges into position, inclined lines are drawn back and forth across the slot with all of the upper ends of the lines meeting the lower ends of the lines above them at the same angle. In this way a continuous zigzag line of very neat and uniform appearance can be quickly drawn on the paper under this drafting instrument. The line can be solid or dotted, or one in which all of the lines inclined in one direction are solid while the rest of the lines are dotted.

In the modification shown in FIG. 3 the base member is a flat plate 20 provided along one edge with a forwardly projecting rib that forms a shoulder 21 extending across the plate. Extending from this shoulder or from points near it to the opposite edge of the base plate are slots 22 through the plate. Each slot has parallel sides, but the slots have different widths so that zigzag lines of different overall widths can be drawn. Disposed on the base plate in engagement with its shoulder is a slide 23, also preferably a flat plate, that has inclined straight edges 24 and 25 that meet midway between the ends of the plate. These edges can be inclined to any desired degree. They are shown with a slope less pronounced than edges 14 and 15 of FIG. 1, but they could have the same or a greater slope.

When the desired width of guide slot is selected, a zigzag line is drawn on paper beneath that slot by moving the slide back and forth along the shoulder 21 in the same manner as explained in connection with FIG. 1. After each movement of the slide, the inclined edge 24 or 25 that extends across the guide slot is used as a guide for drawing an inclined line across the slot on the paper behind it.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A drafting instrument for drawing a zigzag line, comprising a base member having flat front and back surfaces, the back surface being adapted to be placed against a paper sheet and the front surface having an elongated shoulder generally perpendicular to and extending rectilinearly across said front surface, said base member being provided with a guide slot having parallel sides perpendicular to said shoulder, and a slide member disposed against said front surface in sliding engagement therewith and with said shoulder and overlying said slot, the side of the slide member opposite the shoulder having a pair of inclined straight edges converging toward the center of that side at the same angle with respect to a perpendicular line dropped from said shoulder to the intersection of said inclined straight edges, whereby as the slide member is moved back and forth along said shoulder said inclined edges can be used as guides for drawing lines across the slot that are inclined in first one direction and then the other on a paper sheet behind the slot to form a zigzag line.

2. A drafting instrument according to claim 1, in which said base member is provided with a plurality of said guide slots parallel to one another, each of said slots having a different width.

3. A drafting instrument according to claim 1, in which said base member is a plate, and said shoulder extends along one edge of the plate.

4. A drafting instrument according to claim 1, in which said slide member is a flat plate.

5. A drafting instrument according to claim 1, in which said base member includes laterally spaced parts forming said slot between them, and means for adjusting said parts toward and away from each other to vary the width of the guide slot.

6. A drafting instrument according to claim 1, in which said base member includes laterally spaced parts forming said slot between them, one of said parts having a laterally projecting leg overlapping a portion of the front surface of the other part and forming one end of said shoulder, and means adjustably connecting said leg and overlapped part to permit the latter to be ad 5 justed toward and away from the other of said parts to thereby vary the width of the guide slot.

7. A drafting instrument according to claim 1, in which said base member includes laterally spaced parts forming said slot between them, one of said parts having a laterally projecting leg overlapping a portion of the front surface of the other part and forming one end of said shoulder, said leg having a slot extending therethrough parallel to said shoulder, and a releasable fastener extending through said last-mentioned slot and anchored in said overlapped part behind it to normally clamp the overlapped part and said leg tightly together.

8. A drafting instrument according to claim 7, including a ledge parallel to said shoulder extending rearwardly from the edge of said legopposite said shoulder and slidably engaged by the adjacent end of said overlapped part to maintain that part parallel to the other of said parts.

9. A drafting instrument according to claim 8, in which said fastener includes a screw anchored in said overlapped part and having a threaded end projecting from the front of said leg, and a nut screwed onto the projecting end of the screw and against the front of the leg.

10. A drafting instrument according to claim 8, in

which said other part is a flat plate. 

1. A drafting instrument for drawing a zigzag line, comprising a base member having flat front and back surfaces, the back surface being adapted to be placed against a paper sheet and the front surface having an elongated shoulder generally perpendicular to and extending rectilinearly across said front surface, said base member being provided with a guide slot having parallel sides perpendicular to said shoulder, and a slide member disposed against said front surface in sliding engagement therewith and with said shoulder and overlying said slot, the side of the slide member opposite the shoulder having a pair of inclined straight edges converging toward the center of that side at the same angle with respect to a perpendicular line dropped from said shoulder to the intersection of said inclined straight edges, whereby as the slide member is moved back and forth along said shoulder said inclined edges can be used as guides for drawing lines across the slot that are inclined in first one direction and then the other on a paper sheet behind the slot to form a zigzag line.
 2. A drafting instrument according to claim 1, in which said base member is provided with a plurality of said guide slots parallel to one another, each of said slots having a different width.
 3. A drafting instrument according to claim 1, in which said base member is a plate, and said shoulder extends along one edge of the plate.
 4. A drafting instrument according to claim 1, in which said slide member is a flat plate.
 5. A drafting instrument according to claim 1, in which said base member includes laterally spaced parts forming said slot between them, and means for adjusting said parts toward and away from each other to vary the width of the guide slot.
 6. A drafting instrument according to claim 1, in which said base member includes laterally spaced parts forming said slot between them, one of said parts having a laterally projecting leg overlapping a portion of the front surface of the other part and forming one end of said shoulder, and means adjustably connecting said leg and overlapped part to permit the latter to be adjusted toward and away from the other of said parts to thereby vary the width of the guide slot.
 7. A drafting instrument according to claim 1, in which said base member includes laterally spaced parts forming said slot between them, one of said parts having a laterally projecting leg overlapping a portion of the front surface of the other part and forming one end of said shoulder, said leg having a slot extending therethrough parallel to said shoulder, and a releasable fastener extending through said last-mentioned slot and anchored in said overlapped part behind it to normally clamp the overlapped part and said leg tightly together.
 8. A drafting instrument according to claim 7, including a ledge parallel to said shoulder extending rearwardly from the edge of said leg opposite said shoulder and slidably engaged by the adjacent end of said overlapped part to maintain that part parallel to the other of said parts.
 9. A drafting instrument according to claim 8, in which said fastener includes a screw anchored in said overlapped part and having a threaded end projecting from the front of said leg, and a nut screwed onto the projecting end of the screw and against the front of the leg.
 10. A drafting instrument according to claim 8, in which said other part is a flat plate. 